Abrasive blades of the above-described type have found widespread use for cutting contraction joints in concrete highways, airport runways, and the like, and are also useful in the cutting of numerous other hard materials. Improvements in the life expectancy of the abrasive segments have advanced the normal period of usefulness of the abrasive segments to the point where the life of the abrasive segments has exceeded the life of the steel center or support. As a result, failure of the blade frequently occurs because of the wearing through of the steel center just below the place where the abrasive segment is joined to the periphery of the supporting steel center. Consequently, the problem has been presented of finding some ways and means of preventing this premature eroding away of the steel center before the abrasive segments have been completely worn out.
U.S. Pat. No. 2,808,044 discloses the use of "L" shaped or hook shaped segments mounted on the periphery of the steel center to control such erosion. While such solution is helpful in controlling erosion we have found that when the hooks are all of the same lengths, as taught in the prior art, the use of too few hooks does not prevent undercutting, and the use of enough hooks to attempt to prevent such undercutting, results in undercutting below the hook itself.
U.S. Pat. No. 3,128,755, to Benson teaches the use of normal diamond segments on a blade, together with abrasive segments which are deeper than the cutting segments, and which are narrower, in axial width, than the cutting segments.